CN107141312B - A kind of tetrazolium cyano borate ion liquid and preparation method thereof - Google Patents

Abstract

The invention relates to a tetrazolium cyanoboric acid ionic liquid and a preparation method thereof, belonging to the field of organic synthesis and spontaneous combustion liquid propellants. The present invention utilizes sodium tetrazolium cyanoborate and corresponding imidazole, pyrrolidine or pyridine halogenated salt to undergo metathesis reaction in an organic solvent to prepare tetrazolium cyanoboric acid ionic liquid; moreover, the tetrazolium cyanoboric acid ion The liquid has high nitrogen content, positive enthalpy of formation, high density, wide liquid range, low viscosity, good thermal stability and ultra-short ignition delay, and has potential application value in the field of spontaneous combustion liquid propellants . In addition, the present invention also provides a safe and efficient method for preparing sodium tetrazolium cyanoborate, which uses sodium cyanoborohydride and 1H-tetrazole to synthesize sodium tetrazolium cyanoborate in the next step under heating conditions, and the steps are simple. And does not involve highly toxic raw materials.

Description

A kind of tetrazolium cyanoboric acid ionic liquid and preparation method thereof

technical field

The invention relates to a tetrazolium cyanoboric acid ionic liquid and a preparation method thereof, belonging to the field of organic synthesis and spontaneous combustion liquid propellants.

Background technique

Ionic liquids have extremely low vapor pressure, wide liquid range, high energy capacity, and design versatility. Pyrophoric ionic liquids can spontaneously combust when in contact with strong oxidants such as nitric acid and nitrogen tetroxide, and can be used as a substitute for traditional hydrazine fuels that are volatile and toxic. Compared with traditional hydrazine derivative fuels (highly toxic, highly carcinogenic, and highly volatile), energetic ionic liquids are more environmentally friendly as propellant fuels (almost no vapor pressure at room temperature and pressure). The non-volatility and low toxicity of ionic liquids make them very safe as propellant fuels, which are convenient for transportation, storage and practical operation. Among them, some borohydrogen-rich self-igniting ionic liquids have ultra-short ignition delay (ignition delay is less than 5ms) (T.Liu, X.Qi, S.Huang, L.Jiang, J.Li, C.Tang, Q.Zhang, Exploiting hydrophobic borohydride-rich ionic liquids as faster-igniting rocket fuels, Chem.Commun., 2016 ,52,2031; W.Zhang,X.Qi,S.Huang,J.Li,C.Tang,J.Li,Q.Zhang,Bis(borano)hypophosphite-based ionic liquids asultrafast-igniting hypergolic fuels,J. Mater. Chem. A, 2016, 4, 8978). However, due to the high carbon content of most pyrophoric ionic liquids, there is still a gap in terms of density, energy, and specific impulse for practical engineering applications.

At present, there is only one case report on the synthesis of tetrazolium cyanoborate, which is obtained through the ring-forming reaction of sodium isocyanoborohydride and sodium azide, and the synthesis steps of sodium isocyanoborohydride are cumbersome, and the reaction process involves highly toxic Silver cyanide reagent is not conducive to large-scale synthesis (B. Z.Berente, I, Lázár, Synthesis and characterization of cyanohydroisocyanoborates. Reactivity of the isocyano group towards nucleophiles, Polyhedron, 1998, 17, 3175).

Contents of the invention

In view of the defects in the prior art, one of the objects of the present invention is to provide a safe and efficient method for preparing sodium tetrazolium cyanoborate, which is synthesized in one step under heating conditions by sodium cyanoborohydride and 1H-tetrazole Sodium tetrazolium cyanoborate; The second purpose is to provide a tetrazolium cyanoborate ionic liquid, which has a high nitrogen content, positive enthalpy of formation, high density, wide liquid range, lower viscosity, Good thermal stability and ultra-short ignition delay have potential application value in the field of pyrophoric liquid propellants; the third purpose is to provide a method using sodium tetrazolium cyanoborate and corresponding imidazole, pyrrolidine or pyridine halogenated The invention discloses a method for preparing tetrazolium cyanoboric acid ionic liquid through metathesis reaction of salt in an organic solvent, and the method is simple, efficient and mild.

A tetrazolium cyanoborate ionic liquid, the structural formula of the borate ionic liquid is as follows:

Among them, M is R ₁ , R ₂ , R ₃ and R ₄ are each independently an alkyl group or an allyl group containing 1 to 4 carbon atoms.

The M is preferably 1-ethyl-3-methyl-1H-imidazolium cation, 1-butyl-3-methyl-1H-imidazolium cation, 1-allyl-3-methyl-1H-imidazolium cation, 1-ethyl-1-methylpyrrolidinium cation, 1-butyl-1-methylpyrrolidinium cation, 1-ethylpyridine cation, 1-butylpyridine cation, or 1-allylpyridine cation.

A preparation method of tetrazolium cyanoborate ionic liquid of the present invention, the concrete steps of described method are as follows:

Add the cationic halogenated compound corresponding to M and sodium tetrazolium cyanoborate into the organic solvent I, then stir the reaction at 0°C to 50°C for 1d to 15d, cool down, and remove the organic solvent I in the reaction system, Then dissolve with organic solvent II, and carry out vacuum distillation to obtain tetrazolium cyanoboric acid ionic liquid.

The molar ratio of the cationic halogenated compound to the sodium tetrazolium cyanoborate is 1:1-1.5.

The halogen in the cationic halogenated compound is preferably chlorine or bromine; the preferred 1-ethyl-3-methyl-1H-imidazole chloride salt of the cationic halogenated compound, 1-ethyl-3-methyl-1H-imidazole Bromide, 1-Butyl-3-methyl-1H-imidazolium chloride, 1-Butyl-3-methyl-1H-imidazolium bromide, 1-allyl-3-methyl-1H-imidazolium chloride salt, 1-allyl-3-methyl-1H-imidazolium bromide, 1-ethyl-1-methylpyrrolidinium chloride, 1-ethyl-1-methylpyrrolidinium bromide, 1-butan Base-1-methylpyrrolidinium chloride, 1-butyl-1-methylpyrrolidinium chloride, 1-ethylpyridine chloride, 1-ethylpyridine bromide, 1-butylpyridine chloride, 1 -Butylpyridinium bromide, 1-allylpyridinium chloride, or 1-allylpyridinium bromide.

The organic solvent I is preferably one or more of acetonitrile, dichloromethane, tetrahydrofuran and acetone.

The organic solvent II is preferably one or more of dichloromethane, acetone and ethyl acetate.

Preferably, the sodium tetrazolium cyanoborate is prepared by the following method:

Under the protection of protective gas, first add sodium cyanoborohydride to the organic solvent III, then add 1H-tetrazole, then stir the reaction at 50°C-150°C for 3h-72h, cool down, and collect the solid matter in the reaction system ; Use a mixed solution of tetrahydrofuran and dioxane to recrystallize the collected solid matter, and vacuum-dry the solid matter obtained from the recrystallization to obtain sodium tetrazolium cyanoborate.

The protective gas is preferably argon or nitrogen.

The molar ratio of the sodium borohydride to the 1H-tetrazole is 1:1-1.5.

The organic solvent III is preferably at least one of acetonitrile, toluene, tetrahydrofuran and dioxane.

In the mixed solution, the volume ratio of tetrahydrofuran to dioxane is preferably 10˜0.5:1.

Beneficial effect:

(1) The ionic liquid of the present invention has a very high positive enthalpy of formation (mostly ≥ 200kJ·mol ^-1 ), wherein the calculated estimated value of the enthalpy of formation of tetrazolium cyanoborate anion reaches 80kJ·mol ^-1 ; The ionic liquid has a high density (mostly ≥1.10g·cm ^-3 ), among which, the measured values of 1-ethylpyridine tetrazolium cyanoborate and 1-allylpyridine tetrazolium cyanoborate Density 1.17g·cm ^-3 ; the ionic liquid has a high nitrogen content (mostly ≥ 38%), wherein, the nitrogen content of 1-allyl-3-methyl-1H-imidazole tetrazolium cyanoborate up to 42.43%; in addition, the ionic liquid also has a wide liquid range (-70 ° C to its thermal decomposition temperature), very low viscosity (≤16mPa s), good thermal stability (most of the thermal decomposition temperature ≥ 200 ℃), and ultra-short ignition delay (when the oxidant is white fuming nitric acid, the ignition delay is less than 8ms); the tetrazolium cyanoborate ionic liquid of the present invention has potential application in the field of pyrophoric liquid propellant value.

(2) The preparation process of the ionic liquid of the present invention does not involve precious metal silver, and is safe to operate and low in cost; the sodium tetrazolium cyanoborate is synthesized in the next step under heating conditions by sodium cyanoborohydride and 1H-tetrazole Sodium tetrazolium cyanoborate has simple steps and does not involve highly toxic raw materials.

Description of drawings

Fig. 1 is the 1-allyl-3-methyl-1H-imidazolium tetrazolium cyanoborate prepared in Example 1 proton nuclear magnetic spectrum.

Fig. 2 is the carbon NMR spectrum of 1-allyl-3-methyl-1H-imidazole tetrazolium cyanoborate prepared in Example 1.

Fig. 3 is the NMR boron spectrum of 1-allyl-3-methyl-1H-imidazolium tetrazolium cyanoborate prepared in Example 1.

4 is a high-resolution mass spectrum of the 1-allyl-3-methyl-1H-imidazolium tetrazolium cyanoborate cation prepared in Example 1.

5 is a high-resolution mass spectrum of the 1-allyl-3-methyl-1H-imidazolium tetrazolium cyanoborate anion prepared in Example 1.

6 is a DSC chart of 1-allyl-3-methyl-1H-imidazole tetrazolium cyanoborate prepared in Example 1.

Fig. 7 is the H NMR spectrum of 1-ethyl-3-methyl-1H-imidazolium tetrazolium cyanoborate prepared in Example 2.

Fig. 8 is the C NMR spectrum of 1-ethyl-3-methyl-1H-imidazolium tetrazolium cyanoborate prepared in Example 2.

Fig. 9 is the H NMR spectrum of 1-ethylpyridine tetrazolium cyanoborate prepared in Example 3.

Fig. 10 is the carbon NMR spectrum of 1-ethylpyridine tetrazolium cyanoborate prepared in Example 3.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

In the following examples:

Rotary evaporator: model N1001, manufacturer EYELA;

Differential scanning calorimeter: model DSC-60, manufacturer Shimadzu; the heating rate during the test is 5°C/min;

Infrared spectrometer: model ALPHA FT-IR-Spektrometer, manufacturer Bruker;

NMR spectrometer: model AvanceⅢ400M, manufacturer Buruker;

Elemental analyzer: model Vario EL, manufacturer Elementar;

Fourier ion cyclotron transform mass spectrometry: model Apex IV, manufacturer Bruker;

Analytical balance model PL203 used in density measurement, manufacturer METTLER TOLEDO; 5mL density bottle used, manufacturer Beijing Xinweier;

Rheometer: model AR2000EX, manufacturer TA

High-speed camera; Fastcam SA4high speed camera, manufacturer Photron

Ignition test: 50 μL of the ionic liquid prepared in the example was dropped from a height of 15 cm into a 40 mL beaker containing 1.5 mL of white fuming nitric acid. The process was detected by a high-speed camera to obtain the time from the exposure of the ionic liquid to the discovery of an obvious flame , that is, the ignition delay;

Theoretical yield = molar mass of tetrazolium cyanoboric acid sodium salt × molar mass of tetrazolium cyanoboric acid ionic liquid; yield = actual yield/theoretical yield.

Example 1

The preparation steps of 1-allyl-3-methyl-1H-imidazole tetrazolium cyanoborate are as follows:

(1) Under the protection of argon, first add 100mmol sodium cyanoborohydride to 70mL toluene, then add 100mmol 1H-tetrazole, then reflux and stir at 120°C for 6h, cool to room temperature, filter and collect the solid substance; then use a mixed solution of tetrahydrofuran and dioxane (V _{tetrahydrofuran} : V _dioxane =10:1) to recrystallize the collected solid matter, filter to obtain the recrystallized solid, and vacuum-dry to obtain Sodium tetrazolium cyanoborate;

(2) After adding 20mmol 1-allyl-3-methyl-1H-imidazolium chloride salt and 24mmol sodium tetrazolium cyanoborate into 30mL acetonitrile, stir the reaction at 25°C for 7 days, filter and collect the filtrate ; After the acetonitrile solvent in the filtrate was removed by rotary evaporation, dissolve with 50mL dichloromethane, then wash with water three times, then dry with anhydrous sodium sulfate, then carry out vacuum distillation, and finally vacuum dry to obtain 3.789g 1-allyl -3-Methyl-1H-imidazole tetrazolium cyanoborate, yield 82%.

The 1-allyl-3-methyl-1H-imidazole tetrazolium cyanoborate prepared in this example was characterized, and the characterization results were as follows:

¹ H NMR (400MHz, D ₂ O): δ8.78(s,1H), 8.68(s,1H), 7.41(s,2H), 6.05～5.96(m,1H), 5.43～5.32(m,2H ), 4.77(d, J=6Hz, 2H), 3.88(s, 3H), 3.20～2.10(m, 2H), as shown in Figure 1.

¹³ C NMR (100MHz, D ₂ O): δ147.85, 135.36, 130.26, 123.51, 122.18, 121.06, 51.44, 35.65, as shown in FIG. 2 .

¹¹ B (128MHz, D ₂ O): δ-24.75 (t, J=102.7Hz), as shown in FIG. 3 .

IR(KBr): ν=3476, 3149, 3115, 2990, 2403, 2195, 1570, 1165, 1101.

HRMS (ESI) m/z: [M] ⁺ calcd for C ₇ H ₁₁ N ₂ ⁺ : 123.0917, found: 123.0915, as shown in Figure 4; [M] ^- calcd for C ₂ H ₃ BN ₅ ^- : 108.487, found: 108.483, as shown in Figure 5.

Anal.calcd for C ₉ H ₁₅ BN ₁₀ : C 46.78, H 6.11, N 42.43, found: C 46.42, H 6.56, N 41.99.

Calculated by Gaussian 09 (Revision E.01) software, it can be predicted that the enthalpy of formation of the prepared 1-allyl-3-methyl-1H-imidazolium tetrazolium cyanoborate is 427.7kJ·mol ^-1 . According to the DSC test results, it can be seen that the phase transition temperature of the prepared 1-allyl-3-methyl-1H-imidazolium tetrazolium cyanoborate is less than -70°C, and the decomposition temperature is 228°C, see Figure 6 for details. The test shows that the prepared 1-allyl-3-methyl-1H-imidazolium tetrazolium cyanoborate has a density of 1.15 g·cm ^-3 and a viscosity of 7.4 mPa·s. The specific impulse of the prepared 1-allyl-3-methyl-1H-imidazolium tetrazolium cyanoborate can be predicted to be 195s by using the software EXPLO5. From the ignition test results, it can be seen that when the oxidant is white fuming nitric acid, the ignition delay is 3.2ms.

Example 2

Synthesis of 1-ethyl-3-methyl-1H-imidazolium tetrazolium cyanoborate

(1) Under the protection of argon, first add 100mmol sodium cyanoborohydride to 70mL toluene, then add 100mmol 1H-tetrazole, then reflux and stir at 120°C for 6h, cool to room temperature, filter and collect the solid substance; then use a mixed solution of tetrahydrofuran and dioxane (V _{tetrahydrofuran} : V _dioxane =10:1) to recrystallize the collected solid matter, filter to obtain the recrystallized solid, and vacuum-dry to obtain Sodium tetrazolium cyanoborate;

(2) Add 20mmol 1-ethyl-3-methyl-1H-imidazolium chloride salt and 24mmol sodium tetrazolium cyanoborate to 30mL acetonitrile, stir and react at 25°C for 7 days, filter and collect the filtrate; After the acetonitrile solvent in the filtrate was removed by rotary evaporation, it was first dissolved with 50 mL of dichloromethane, then washed with water three times, then dried with anhydrous sodium sulfate, then subjected to vacuum distillation, and finally vacuum-dried to obtain 3.549 g of 1-ethyl-3 -Methyl-1H-imidazole tetrazolium cyanoborate, yield 81%.

The 1-ethyl-3-methyl-1H-imidazole tetrazolium cyanoborate prepared in this example was characterized, and the characterization results were as follows:

¹ H NMR (400MHz, D ₂ O): δ8.77(s, 1H), 8.65(s, 1H), 7.42～7.30(m, 2H), 4.18(q, J=7.2Hz, 2H), 3.86( s, 3H), 3.20 ~ 2.10 (m, 2H), 1.45 (t, J = 7.6Hz, 3H), as shown in Figure 7.

¹³ C NMR (100MHz, D ₂ O): δ147.82, 135.40, 123.39, 121.80, 44.75, 35.59, 14.38, as shown in FIG. 8 .

¹¹ B (128 MHz, D ₂ O): δ-24.78 (t, J = 101.1 Hz).

IR(KBr): ν=3480, 3152, 3115, 2988, 2403, 2320, 2195, 1568, 1470, 1356, 1101.

HRMS (ESI): m/z: [M] ⁺ calcd for C ₆ H ₁₁ N ₂ ⁺ : 111.0917, found: 111.0916; [M] ^- calcd for C ₂ H ₃ BN ₅ ^- : 108.487, found: 108.0483.

Anal.calcd for C ₈ H ₁₄ BN ₇ : C 43.86, H 6.44, N 44.76, found: C 44.24, H 5.92, N 44.06.

Calculated by Gaussian 09 (Revision E.01) software, it can be predicted that the enthalpy of formation of the prepared 1-ethyl-3-methyl-1H-imidazolium tetrazolium cyanoborate is 256.8kJ·mol ^-1 . After testing, it can be seen that the phase transition temperature of the prepared 1-ethyl-3-methyl-1H-imidazole tetrazolium cyanoborate is less than -70°C, and the thermal decomposition temperature is 233°C; the density is 1.12g·cm ^{- 3} , the viscosity is 7.1mPa·s. The specific impulse of the prepared 1-ethyl-3-methyl-1H-imidazole tetrazolium cyanoborate can be estimated to be 184s by using the software EXPLO5. From the ignition test results, it can be seen that when the oxidant is white fuming nitric acid, the ignition delay is 1.4ms.

Example 3

Synthesis of 1-ethyl-pyridine tetrazolium cyanoborate

(1) Under the protection of argon, first add 100mmol sodium cyanoborohydride to 70mL toluene, then add 100mmol 1H-tetrazole, then reflux and stir at 120°C for 6h, cool to room temperature, filter and collect the solid substance; then use a mixed solution of tetrahydrofuran and dioxane (V _{tetrahydrofuran} : V _dioxane =10:1) to recrystallize the collected solid matter, filter to obtain the recrystallized solid, and vacuum-dry to obtain Sodium tetrazolium cyanoborate;

(2) Add 20mmol 1-ethyl-pyridinium bromide and 24mmol sodium tetrazolium cyanoborate to 30mL of acetonitrile, stir and react at 25°C for 7 days, filter and collect the filtrate; remove the acetonitrile in the filtrate by rotary evaporation After the solvent was dissolved, it was first dissolved with 50 mL of dichloromethane, then washed with water three times, then dried with anhydrous sodium sulfate, then subjected to vacuum distillation, and finally vacuum-dried to obtain 3.846 g of 1-ethyl-pyridine tetrazolium cyanoborate , yield 89%.

The 1-ethyl-pyridine tetrazolium cyanoborate prepared in this embodiment was characterized, and the characterization results were as follows:

¹ H NMR (400MHz, D ₂ O): δ8.83～8.82(m,2H), 8.76(s,1H), 8.49(s,1H), 8.04～8.03(m,2H), 4.629(q,J =7.6Hz, 2H), 3.2～2.1(m, 2H), 1.62(t, J=7.2Hz, 3H), as shown in Figure 9.

¹³ C NMR (100MHz, D ₂ O): δ147.84, 145.38, 143.83, 128.19, 57.32, 15.59, as shown in FIG. 10 .

¹¹ B (128 MHz, D ₂ O): δ-24.76 (t, J = 102.0 Hz).

IR(KBr): ν=3487, 3134, 3066, 2984, 2943, 403, 21930, 1636, 1489, 1468, 1177, 1140, 1101;

HRMS (ESI) m/z: [M] ⁺ calcd for C ₇ H ₁₀ N ⁺ : 108.0808, found: 108.0804; [M] ^- calcd for C ₂ H ₃ BN ₅ ^- : 108.487, found: 108.484.

Anal.calcd for C ₁₁ H ₁₈ BN ₉ : C 50.03, H 6.07, N 38.90, found: C 49.61, H 6.27, N 38.47.

Calculated by Gaussian 09 (Revision E.01) software, it can be predicted that the enthalpy of formation of the prepared 1-ethylpyridine tetrazolium cyanoborate is 299.3kJ·mol ^-1 . The test shows that the prepared 1-ethylpyridine tetrazolium cyanoborate has a phase transition temperature of less than -70°C, a decomposition temperature of 175°C, a density of 1.17g·cm ^-3 and a viscosity of 9.3mPa·s. The specific impulse of the prepared 1-ethylpyridine tetrazolium cyanoborate can be estimated to be 183s by using the software EXPLO5. From the ignition test results, it can be seen that when the oxidant is white fuming nitric acid, the ignition delay is 2.6ms.

To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (4)

1. a preparation method of tetrazolium cyanoboronic acid ionic liquid, is characterized in that: the concrete steps of described method are as follows: Add the cationic halogenated compound corresponding to M and sodium tetrazolium cyanoborate into the organic solvent I, then stir the reaction at 0°C to 50°C for 1d to 15d, cool down, and remove the organic solvent I in the reaction system, Then dissolve with organic solvent II, and carry out vacuum distillation to obtain tetrazolium cyanoboric acid ionic liquid; Wherein, the molar ratio of the cationic halogenated compound corresponding to M to the sodium tetrazolium cyanoborate is 1:1～1.5; the structural formula of the prepared tetrazolium cyanoborate ionic liquid is as follows: The cationic halogenated compound corresponding to M is 1-ethyl-3-methyl-1H-imidazolium chloride, 1-ethyl-3-methyl-1H-imidazolium bromide, 1-butyl-3-methyl -1H-imidazolium chloride, 1-butyl-3-methyl-1H-imidazolium bromide, 1-allyl-3-methyl-1H-imidazolium chloride, 1-allyl-3-methyl -1H-imidazolium bromide, 1-ethyl-1-methylpyrrolidinium chloride, 1-ethyl-1-methylpyrrolidinium bromide, 1-butyl-1-methylpyrrolidinium chloride, 1 -Butyl-1-methylpyrrolidinium bromide, 1-ethylpyridinium chloride, 1-ethylpyridine bromide, 1-butylpyridine chloride, 1-butylpyridine bromide, 1-allyl Pyridinium chloride, or 1-allyl pyridinium bromide; Organic solvent I is more than one of acetonitrile, dichloromethane, tetrahydrofuran and acetone; The organic solvent II is at least one of dichloromethane, acetone and ethyl acetate. 2. the preparation method of a kind of tetrazolium cyanoboric acid ionic liquid according to claim 1, is characterized in that: described tetrazolium cyanoboric acid sodium salt adopts following method to prepare, Under the protection of protective gas, first add sodium cyanoborohydride to the organic solvent III, then add 1H-tetrazole, then stir the reaction at 50°C-150°C for 3h-72h, cool down, and collect the solid matter in the reaction system ; Recrystallize the collected solid matter with a mixed solution of tetrahydrofuran and dioxane, and vacuum-dry the solid matter obtained by recrystallization to obtain sodium tetrazolium cyanoborate; Wherein, the protective gas is argon or nitrogen; the molar ratio of the sodium borohydride to 1H-tetrazole is 1:1-1.5. 3. The preparation method of a tetrazolium cyanoborate ionic liquid according to claim 2, characterized in that: the organic solvent III is more than one of acetonitrile, toluene, tetrahydrofuran and dioxane. 4. The preparation method of a tetrazolium cyanoborate ionic liquid according to claim 2, characterized in that: in the mixed solution, the volume ratio of tetrahydrofuran to dioxane is 10-0.5:1.